Can someone give me a hint why my cron job aren’t running?

I’m with Ubuntu 16 and that’s the content of my crontab file:

*/1 * * * * cd /home/openproject/openproject-ce; RAILS_ENV="production" ./bin/rake jobs:workoff

This command works when running manually and a simple log command worked too.

I already tried all the variations suggested here: https://askubuntu.com/questions/23009/why-crontab-scripts-are-not-working

I solved the issue after reading this:
https://stackoverflow.com/questions/31482131/only-with-cron-usr-bin-env-ruby-executable-hooks-no-such-file-or-directory